Is Shed Storage Detrimental To Valves?

[Fidelity Fan]

I have stored in my shed a large amount of valves for over three decades.

I recently tried two of these, that are UCL83s in a BRC record player. There was low fluctuating distorted sound from them.

This week I bought as seen a Hacker Gondolier AL42 speaker unit. It came with one of the ECL86s broken. I only had one spare ECL86 (that had previously been stored in my shed for years). I got low distorted sound with this too. ECL86s are now very expensive.

A few years ago, I bought a number of new Polish made PCL86s with a view to using them in my GP42 as replacement for the ECL86s should they fail. I know that the heater supply would need changing from 6.3v to 13v. However, as a quick test I tried a PCL86 in the AL42 with the other good ECL86 in situ. It worked well, proving that the ECL86 stored all those years was defective. I am sure that it worked prior to storage, as it was taken from another record player I scrapped in the late 1980s. The AL42 has the mustard grid coupling capacitors that don't usually go leaky.

So my question is does cold and damp storage damage valves?

[ben]

I suppose that changes in temperature might weaken vulnerable parts of the glass over time, or exacerbate weaknesses present since manufacture. This would lead to loss of vacuum and consequent ingress of air, moisture, etc.
I suppose the pins are the most at risk from damp. Apart form that I cannot think of anything that could harm them. I'm sure others more knowledegable of the physics side of things will offer a better insight!

[Station X]

You're assuming that the distorted sound is down to the valves. It's more likely caused by other components which are more prone to aging.

[Fidelity Fan]

I proved it was the valves by swapping them. As I pointed out, the Hacker AL42 played fine
as a quick test with a PCL86 in place of my suspected faulty ECL86.

[PsychMan]

It doesnt prove the valve is defective, for one thing I believe that amp uses the 2x ECL86s in a push pull configuration. So in addition to other component issues, you could have a major mismatch between the 2 ECL86s.

I would have thought if the vacuum of a valve was still good, and it wasn't suddenly taken from a freezing shed and given power applied immediately, then it wouldn't have suffered...

[Station X]

This thread begs the question "What faults INSIDE a valve can lead to distortion?

[ben]

Good point, Graham. Which in turn suggests that we're dealing with manufacturing impurities/defects, rather than storage as a factor.

[ms660]

Leakage and low emission can cause distortion.

Lawrence.

[Sideband]

Originally Posted by Fidelity Fan

I know that the heater supply would need changing from 6.3v to 13v. However, as a quick test I tried a PCL86 in the AL42 with the other good ECL86 in situ. It worked well, proving that the ECL86 stored all those years was defective.

So if the PCL86 has a 13.3V heater and the ECL86 has a 6.3V heater, how did the PCL86 light up with only 6.3V? Surely it wouldn't have worked and even if the heater did give the faintest of glows, it couldn't possibly have worked anywhere near efficiently.

I suspect you have other problems......

[JonSnell]

The only problem storing valves in a shed or workshop is the discolouration of the pins. No other problems can, in my experience, occur.
Temperature does not affect them nor does air pressure/moisture etc.
Any distortion is probably due to either external components, bias setting or maybe the valve was faulty before storage.
I have valves that I stored from the 1960s and never had an issue. Number 83, mercury vapour rectifiers can condense their mercury within the glass but that soon restores after a few minutes of use.
There are so called HiFi experts that freeze valves before sale, adding 'cryogenicly sorted' to their sales blurb and some people actually pay over the top for them!
A fool and his money, is easily parted.

[ms660]

As said the PCL86 is twice the heater voltage of the ECL86 so I can't see the PCL86 doing much, the amplifier would still work though with one ECL86 working due to the fact that it's cathode is biased at 7.8 volts.

Lawrence.

[lesmw0sec]

I'd go along with Jon. I have an R1155 which apart from years of misuse had ended up in a skip. I had to strip everything, remove corrosion,restore the chassis and renovate the front panel, but the valves (which are even older than me) are working well years after.

[Sideband]

Originally Posted by ms660

As said the PCL86 is twice the heater voltage of the ECL86 so I can't see the PCL86 doing much, the amplifier would still work though with one ECL86 working due to the fact that it's cathode is biased at 7.8 volts.

Lawrence.

Yes that's a good point so one faulty ECL86 of the pair could cause the distortion. Removing that and replacing with a PCL86 which wouldn't light up or do anything is the same as not replacing it....if you see what I mean.

[G6Tanuki]

I've got a selection of valves recovered from spending at least 40 years in a 'shed' which had during those four decades biodegraded-away to a pile of rotten wood and rusty corrugated-iron.

Some of the valves had moss on them! But they all still worked fine and I'm using several of them [a Mazda AC/HL, Cossor 42OT and a pair of Marconi ML4] to this day without any indication that their moist hibernation has done them any harm.

[NottsIan]

On the other hand, I had a box of valves stored in a cold, damp garage for a couple of years and every single one of them developed a white getter.

[David Simpson]

Storage of valves, or any components, in a damp shed is a definite NO NO. Likewise storing radios & test equipment. Then there are issues with mains supply's safety.
Shed construction/de-humidifier's effectiveness/electrical safety/damp-proof storage etc. have been banged-on to a massive degree in numerous Forum thread posts in the last two or three years. Have a good shufti through "Search".

Regards, David

[paulsherwin]

Valves can survive poor storage, but it's not a wise thing to do. In addition to rusty pins and failed glue you can get a failure of the pin-glass seal in all-glass types which allows them to go to air. This seems to be the result of repeated temperature cycling.

[Radio_Dave]

Carefully check the valve base. I've had a couple valves, stored in damp conditions, which had gone to air because the pins have corroded, swollen and cracked the glass base.


David

[HamishBoxer]

The amount of stuff I see these days looks as most of it comes from damp sheds etc.

[AmateurRepairer]

Keep them in potato boxes wrapped in news paper, taped up, then surrounded by straw, if I can keep eggs safe in the back of a pickup this way all night and day on a busy farm they will be fine in a shed not moving!